A randomized, double-blind, placebo-controlled, cross-over study to evaluate analgesic activity of Terminalia chebula in healthy human volunteers using a mechanical pain model.

Background And Aims: To evaluate analgesic activity and safety of single oral dose (1000 mg) of Terminalia chebula using a mechanical pain model in healthy human volunteers.

Material And Methods: Twelve healthy volunteers were randomized to receive either single oral dose of 2 capsules of T. chebula 500 mg each or identical placebo capsules in a double-blinded manner. Mechanical pain was assessed using Ugo basile analgesy meter (Randall-Selitto test) before and 3 h after administration of test drug. The parameters evaluated were pain threshold force and time; pain tolerance force and time. A washout period of 1-week was given for crossover between active drug and placebo.

Results: Terminalia chebula significantly increased the mean percentage change for pain threshold force and time, and pain tolerance force and time compared to placebo (P < 0.001). The mean percentage change for pain threshold force and time (20.8% and 21.0%) was increased more than that of pain tolerance force and time (13.4% and 13.4%). No adverse drug reaction was reported with either of the study medications during the study period.

Conclusion: T. chebula significantly increased pain threshold and pain tolerance compared to placebo. Both the study medications were well tolerated. Further multiple dose studies may be needed to establish the analgesic efficacy of the drug in patients suffering from osteoarthritis, rheumatoid arthritis and other painful conditions.